Iowa State's 6-Piece Solar Home: Solar Decathlon

To see how the newest innovations in solar power and energy efficiency can be incorporated into homes, we headed down to the Solar Decathlon on the National Mall in Washington, D.C. The competition, run by the Department of Energy (and sponsored in part by Popular Mechanics), pits 20 college teams against one another in a showdown of architecture and engineering.

Iowa State's Interlock House, which breaks down into six modules, is without a doubt high-tech. A quick look at the inverters inside its mechanical closet shows the home's two kinds of solar panels--crystalline silicon and thin-film--are producing 1952 watts of electricity. An evacuated tube solar thermal system sends heat to the HVAC system or to radiant tubing in the floor. It also recharges a desiccant system for removing humidity from the air. "But it's not going to intimidate anybody," Mike Berg, a fifth year senior at Iowa State, says.

And that in itself was a design choice made by Iowa State's Solar Decathlon team. "In the next 10 to 15 years a high percentage of the population will be older than 65," Brent Nie, an undergraduate architecture student, says. "We wanted to design a house that met that demand." As a result, the Interlock House meets all regulations for accessibility under the Americans with Disabilities Act. It's intended as transitional housing--mainly for seniors who want to downsize from a larger family home, but who still want to live ind

The cedar-sided home is insulated with a soybean-based spray. A sun porch, which opens to the outdoors and in via folding NanaWalls, can provide ventilation on nice days and warmth on cold ones. The sun beams in and heats dark tiles on the porch's floor, warming the foyer. Opening windows above the interior NanaWalls lets the heat into the home. PV-covered louvers over the windows on the south side also allow residents to modulate solar gain, maintaining a comfortable indoor climate.